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What happens when you don't adjust the valves on a slant?
https://www.slantsix.org/forum/viewtopic.php?t=18208		 Page 1 of 2
Author:  Reed [ Fri Jun 23, 2006 5:28 pm ]
Post subject:  What happens when you don't adjust the valves on a slant?
I know a guy over on www.vannin.com who has a very nice custom mid 70s dodge van powered by a slant. He says it runs great but he doesn't want to adjust the val;ves because it sounds to "tech" to him. I have told him that the valves need to be adjusted as part of the regular maintenance of the engine but he still doesn't want to adjust them.

What will happen if he never adjusts the valves?
Author:  dakight [ Fri Jun 23, 2006 5:35 pm ]
Post subject: 
The clearances will eventually tighten up, the engine will begin to run poorly and finally one or more valves is likely to burn and need replacement. It's even possible that a valve could fail due to excess heat resulting in catastrophic destruction of the engine,
Author:  SlantSixDan [ Fri Jun 23, 2006 5:55 pm ]
Post subject: 
Quote:
The clearances will eventually tighten up
Some of them might. More commonly, though, the clearances will tend to loosen, causing the engine to grow noisier, less efficient and less powerful. Neither result is good news; Slants run best with properly-adjusted valves.
Quote:
It's even possible that a valve could fail due to excess heat resulting in catastrophic destruction of the engine,
A failed valve does not result in catastrophic destruction of the engine, just a dead cylinder until the failed valve is repaired.
Author:  emsvitil [ Fri Jun 23, 2006 6:50 pm ]
Post subject: 
Quote:
Quote:
The clearances will eventually tighten up
Some of them might. More commonly, though, the clearances will tend to loosen, causing the engine to grow noisier, less efficient and less powerful. Neither result is good news; Slants run best with properly-adjusted valves.
Quote:
It's even possible that a valve could fail due to excess heat resulting in catastrophic destruction of the engine,
A failed valve does not result in catastrophic destruction of the engine, just a dead cylinder until the failed valve is repaired.

It would be catastrophic if the head breaks off..........
Author:  Slant n' Rant [ Fri Jun 23, 2006 6:58 pm ]
Post subject: 
Even though ive never had the 'pleasure' to adjust my valves on my slant(or anything else for that matter) im eager for the experience. Thats what i like most about slants and inline engines alike, theres just the one bank to work on, unlike a v8 which is just double the work for spark plugs, valve adj. manifold, head etc. How low tech can you get? How about a big block with 32 valves? then even i would throw in the towel :P
Author:  SlantSixDan [ Fri Jun 23, 2006 7:01 pm ]
Post subject: 
Quote:
It would be catastrophic if the head breaks off..........
Not gonna happen.
Author:  Tim Keith [ Fri Jun 23, 2006 7:51 pm ]
Post subject: 
The '80s hydraulic valve motors are quiet and require no adjustment. You might consider using that setup.
Author:  SlantSixDan [ Fri Jun 23, 2006 8:41 pm ]
Post subject: 
Quote:
The '80s hydraulic valve motors are quiet and require no adjustment. You might consider using that setup.
True, but the stock cam is weak, there's limited availability of decent aftermarket cams, and retrofitment of the hydraulic lifter setup requires block mods.
Author:  MitchB [ Sat Jun 24, 2006 7:19 am ]
Post subject:  Re: What happens when you don't adjust the valves on a slant
Quote:
What will happen if he never adjusts the valves?
More than likely the lash will loosen over time. This will result in higher than normal valvetrain wear and give an abnormal wear pattern on the camshaft. The cam lobes have a clearance ramp designed to gently take up the lash before opening the valves. If the lash becomes excessive, the cam begins opening the valves before all the lash is taken up. This area of the lobe has a much higher acceleration rate than the clearance ramp. Once operated over time in this state, it often becomes impossible to restore quiet lifter operation with an adjustment because the cam has now worn on the opening part of the lobes which is past the clearance ramps.

Mitch
Author:  Reed [ Sat Jun 24, 2006 8:27 am ]
Post subject: 
Thanks guys! I will tell him to check out this thread and hopefuly he will change his mind.
Author:  Mel Ott [ Sat Jun 24, 2006 9:12 am ]
Post subject:  Re: What happens when you don't adjust the valves on a slant
Quote:
Quote:
What will happen if he never adjusts the valves?
More than likely the lash will loosen over time. This will result in higher than normal valvetrain wear and give an abnormal wear pattern on the camshaft. The cam lobes have a clearance ramp designed to gently take up the lash before opening the valves. If the lash becomes excessive, the cam begins opening the valves before all the lash is taken up. This area of the lobe has a much higher acceleration rate than the clearance ramp. Once operated over time in this state, it often becomes impossible to restore quiet lifter operation with an adjustment because the cam has now worn on the opening part of the lobes which is past the clearance ramps.

Mitch
I have to disagree here .......
With my quite a few years experience with not only the Slanter but
also the V 8's, I have to say that SlantSixDan is right on the money
with his explaination.
What he said is what will happen 99 % of the time.
Author:  dakight [ Sat Jun 24, 2006 7:29 pm ]
Post subject: 
Quote:
Quote:
It would be catastrophic if the head breaks off..........
Not gonna happen.
I've seen it happen. Granted, it wasn't on a slant ( I think it was a Ford V8 but it's been a long time so I'm not sure ) but an exhaust valve head broke off at the stem and cratered the piston which in turn did a number on the cylinder walls. It wasn't pretty but it was spectacular.
Author:  MitchB [ Sat Jun 24, 2006 10:24 pm ]
Post subject: 
Quote:
Quote:
Quote:
What will happen if he never adjusts the valves?
More than likely the lash will loosen over time. This will result in higher than normal valvetrain wear and give an abnormal wear pattern on the camshaft. The cam lobes have a clearance ramp designed to gently take up the lash before opening the valves. If the lash becomes excessive, the cam begins opening the valves before all the lash is taken up. This area of the lobe has a much higher acceleration rate than the clearance ramp. Once operated over time in this state, it often becomes impossible to restore quiet lifter operation with an adjustment because the cam has now worn on the opening part of the lobes which is past the clearance ramps.

Mitch
I have to disagree here .......
With my quite a few years experience with not only the Slanter but
also the V 8's, I have to say that SlantSixDan is right on the money
with his explaination.
What he said is what will happen 99 % of the time.
Please read my post again and explain your comment.

Thanks

Mitch
Author:  Ralph Zini [ Sun Jun 25, 2006 12:34 am ]
Post subject: 
To Reed, et al.

Too much clearance means that the rocker arm hammers on the valve stem and increases it's diameter at the top. Then in order to remove the valves, the tops of the stems need to be reduced in diameter by grinding. The rocker arms may also become mushroomed.
The loss of power is from the reduced lift & duration, and the excess clearance, in effect, retards the cam. If the clearance becomes really excessive, the valves will start to slam when seating, because the closing ramp is now part of the valve clearance. This is really bad for the valve head and the seat.

Ralph
Author:  emsvitil [ Sun Jun 25, 2006 12:36 am ]
Post subject: 
I'm going to throw in that exhaust valves without hardened valves seat will tighten up and not loosen.........


BTW, My exhaust valves are receding. :cry:
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